1. Field of the Invention
The present invention relates to an information recording medium where a magnetic layer is formed on at least one side of a substrate.
2. Description of the Related Art
Increases in areal recording density of a magnetic recording medium (information recording medium) such as a hard disk have conventionally been achieved by increasing both the linear recording density and the track density. To achieve further increases in areal recording density in the future, both linear recording density and track density will have to be raised further. Methods of increasing the linear recording density include improving the recording resolution of a magnetic head and increasing the coercive force and/or reducing the noise for the magnetic recording medium, with the spacing between the magnetic head and the magnetic recording medium also being reduced.
On the other hand, various problems have emerged relating to the raising of track density, such as the occurrence of side fringes and crosstalk due to the head magnetic field spreading and the limit on how small the head can be made, so that with conventional methods, there is a limit on how much track density, and in turn areal recording density, can be increased. For this reason, a discrete track-type magnetic recording medium that has a recording layer formed in a predetermined convex/concave pattern has been proposed as a magnetic recording medium for which the areal recording density can be further increased. For this type of discrete track-type magnetic recording medium, there is a known problem in that the fly characteristics of the magnetic head deteriorate due to the effects of the concave parts in the convex/concave pattern. As a means of solving this problem, a magnetic disk disclosed by Japanese Laid-Open Patent Publication No. H09-97419 is known. This magnetic disk includes a guard band member formed by filling the concave parts (guard band spaces) in the convex/concave pattern with a non-magnetic material. In this case, the surface of the magnetic disk is polished to produce a state where there is no difference in height between the recording magnetic member and the guard band member, that is, a state where the surface of the magnetic disk has been made smooth.